A new book by St. Petersburg historian, candidate of historical sciences A. A. Lebedev is dedicated to the failed Bosphorus expedition of 1853, which was the last chance for the sailing Black Sea Fleet to capture Constantinople. The refusal to carry it out caused negative consequences for the Russian state. Despite a significant number of works devoted to the history of the Crimean War of 1853-1856, questions still remain on this subject, which the author of the study is trying to answer, having undertaken an analysis of the preparation plans for the Bosphorus operation in 1835-1853. CONTENTS: Introduction 4Chapter 1. Background to the problem, or what historical experience has shown 6Chapter 2. “This enterprise is dangerous, difficult, but which, given our means, should not and cannot fail”: the Bosphorus operation in 1838-1850. 15Chapter 3. “The naval enterprise to Constantinople is either very difficult, or even impossible”: the Bosphorus operation in 1853. 70Instead of a conclusion, or why the landing in the Bosphorus did not take place in 1853 107Appendices 113Notes 154List of sources and literature used 167